This invention relates to novel compounds used as polymerizable monomers in a dental adhesive composition, and having a general formula (1): ##STR2## wherein R.sup.2 is a carboxyl group and R.sup.3 is a hydrogen atom when R.sup.1 is a methyl group, and R.sup.2 is a hydroxyl group and R.sup.3 is a carboxyl group when R.sup.1 is a hydrogen atom. They are N-methyl-N-(2-hydroxy-3-methacryloyloxypropyl)-m-aminobenzoic acid and 2-hydroxy-4-[(2-hydroxy-3-methacryloyloxypropyl)-amino]benzoic acid.
For the treatment of dental caries, composite resins were developed as a substitute for conventional dental cements such as zinc phosphate cement and silicate cement. Recently, improved composite resins are available which are stable for a prolonged period of time, because of reduced water-absorption and degradation, and exhibit very little difference in color from natural teeth.
However, since composite resins do not essentially adhere to tooth enamel or dentin, there is the likelihood that a gap is formed between tooth cavity and composite resin embedded therein over a long period of time. Such a gap tends to facilitate secondary caries and eventually a filled composite resin will fall from the cavity.
To improve the adhesion between composite resin and cavity wall, a variety of adhesion promotors or adhesive liners have been developed. Also proposed are adhesive caries-preventive filling materials, malaligned tooth orthodontic adhesives, and other dental adhesive compositions which solely aim at firm adhesion to tooth substances. Most of them have problems with respect to durability in the mouth and easiness of handling and few materials can firmly adhere to tooth for a long period of time in a wet, temperature-varying environment like the mouth.